newbie battery and electrical question
Hi all, new to the forum, bought a 04 E350 to do a camper conversion. so i am considering the electrical things now, just got a norcold 740bb fridge that draws 3.75amp under 12v mode, planning t...
Forum Discussion
OK lets go through this.
You strongly disagree with the statements about multistep chargers and insist on supporting data (which was given proving the statements) for mutistep chargers being the charger of choice for Lifeline, claim that a single step charger is fine for AGMs based on the recommendation they can be used as starters (more on that later), recommend an AGM and single step charger to the OP, claim that Lifeline says single step chargers are good (with no supporting data), and then wonder at the choice of words that indicate you are saying a single step is the "preferred" charger per Lifeline. That is stretching semantics way to far from intent.
I have been unable to find any information from AGM folks that say it is OK to use a single step charger, unless you manually watch it, time, measure amps, and disconnect when needed. I would like to see some.
The size of the chargers on the Lifeline link is not the issue that they were posted for. They were, and do, show that Lifeline recommends multistep chargers, not singles. What is the point?
If you use a single step, what voltage do you chose. 13.5v will leave you undercharged and losing capacity. 14.4v, which the manufacturers want to get the batteries full, will dry out the electrolyte if left on full batteries, and lose you capacity. Voltage in between, best/worst of both? Multistep takes care of that for you.
How about the fact that manufacturers will say it is OK to use an AGM as a starting battery, and be charged by the vehicle alternator, so it is OK on a single step charge when used as a coach battery? These are two separate, and distinct, applications, and shouldn't be lumped together, IMO, and from discussions with Lifeline, Deka, Optima, and Trojan over the last 30 years, they consider them different also. Optima is the primary one recommending using them for starters, and claim a higher voltage tolerance than the other brands, up to 15 volts, but they throw in a battery temp disclaimer. I specifically asked about how they do it, and they wouldn't say (not surprising), but it probably has to do with heat dissipation (they have lower AH for their size than most), and they may have a voltage limiter in them. Regardless of that, I asked about the electrolyte dry out issue at the 14.4+ volts vehicles now run (our hotrod, that we use an Optima in, runs at 13.8 volts like most older stuff), and they said it would be an issue if the battery saw the voltage for very long times, but the way vehicles are used in real life, they rarely get the battery totally full, much less full and held there with the high voltage for long periods, so it turns out to not be an issue, except in a very few special cases. That makes perfect sense to me. Use in an RV, at least the way many folks use it, would not be the same. If you have a separator, and come off shore power, all your batteries are full, and could easily see high alternator voltage for 12+ hours of driving, which could easily be damaging, both for the starter and coach batteries, at least according to the techs I talked to. A battery disconnect was recommended to me when I considered AGMs when I increased our battery bank size. Using one for the starter, was not recommended. Boats that are motored a lot, and thus see a lot of alternator voltage, often use a 12v to 12v multistep chargers to address the issue. A single step charger would have all the same issues as a long drive, if it was set at the battery manufacturer recommended voltage of 14.1-14.4 volts (most common). Many, many, folks (us included) leave our RVs plugged in at home for weeks at a time. How do you handle that with a single step charger?
You didn't give a model number for he Parallax charger, but when I look at them, most look to be power supplies set at about 13.6 volts, which is too low to fill batteries completely. Some have a "boost" mode, which takes them to the appropriate higher voltage to get a good full charge, but those are multistep, albeit manually, chargers, so you would say they are not needed.
I don't think you would get any AGM manufacturer to recommend using a single step charger in these kind of applications, unless you had a fixed discharge every cycle and fixed recharge time, with a fixed bank size. I would love to hear if you have a source that would.
You strongly disagree with the statements about multistep chargers and insist on supporting data (which was given proving the statements) for mutistep chargers being the charger of choice for Lifeline, claim that a single step charger is fine for AGMs based on the recommendation they can be used as starters (more on that later), recommend an AGM and single step charger to the OP, claim that Lifeline says single step chargers are good (with no supporting data), and then wonder at the choice of words that indicate you are saying a single step is the "preferred" charger per Lifeline. That is stretching semantics way to far from intent.
I have been unable to find any information from AGM folks that say it is OK to use a single step charger, unless you manually watch it, time, measure amps, and disconnect when needed. I would like to see some.
The size of the chargers on the Lifeline link is not the issue that they were posted for. They were, and do, show that Lifeline recommends multistep chargers, not singles. What is the point?
If you use a single step, what voltage do you chose. 13.5v will leave you undercharged and losing capacity. 14.4v, which the manufacturers want to get the batteries full, will dry out the electrolyte if left on full batteries, and lose you capacity. Voltage in between, best/worst of both? Multistep takes care of that for you.
How about the fact that manufacturers will say it is OK to use an AGM as a starting battery, and be charged by the vehicle alternator, so it is OK on a single step charge when used as a coach battery? These are two separate, and distinct, applications, and shouldn't be lumped together, IMO, and from discussions with Lifeline, Deka, Optima, and Trojan over the last 30 years, they consider them different also. Optima is the primary one recommending using them for starters, and claim a higher voltage tolerance than the other brands, up to 15 volts, but they throw in a battery temp disclaimer. I specifically asked about how they do it, and they wouldn't say (not surprising), but it probably has to do with heat dissipation (they have lower AH for their size than most), and they may have a voltage limiter in them. Regardless of that, I asked about the electrolyte dry out issue at the 14.4+ volts vehicles now run (our hotrod, that we use an Optima in, runs at 13.8 volts like most older stuff), and they said it would be an issue if the battery saw the voltage for very long times, but the way vehicles are used in real life, they rarely get the battery totally full, much less full and held there with the high voltage for long periods, so it turns out to not be an issue, except in a very few special cases. That makes perfect sense to me. Use in an RV, at least the way many folks use it, would not be the same. If you have a separator, and come off shore power, all your batteries are full, and could easily see high alternator voltage for 12+ hours of driving, which could easily be damaging, both for the starter and coach batteries, at least according to the techs I talked to. A battery disconnect was recommended to me when I considered AGMs when I increased our battery bank size. Using one for the starter, was not recommended. Boats that are motored a lot, and thus see a lot of alternator voltage, often use a 12v to 12v multistep chargers to address the issue. A single step charger would have all the same issues as a long drive, if it was set at the battery manufacturer recommended voltage of 14.1-14.4 volts (most common). Many, many, folks (us included) leave our RVs plugged in at home for weeks at a time. How do you handle that with a single step charger?
You didn't give a model number for he Parallax charger, but when I look at them, most look to be power supplies set at about 13.6 volts, which is too low to fill batteries completely. Some have a "boost" mode, which takes them to the appropriate higher voltage to get a good full charge, but those are multistep, albeit manually, chargers, so you would say they are not needed.
I don't think you would get any AGM manufacturer to recommend using a single step charger in these kind of applications, unless you had a fixed discharge every cycle and fixed recharge time, with a fixed bank size. I would love to hear if you have a source that would.
